Effects of Different Light Qualities on the Growth Characteristics of Populus trinervis

Populus trinervis is native to China and plays an irreplaceable role in maintaining the ecological balance of boreal and temperate forests.P.trinervis mainly grows in high-altitude areas.At present,there are limited studies on the response of P.trinervis to different light qualities,so it is necessary to investigate the photosynthetic physiological changes of P.trinervis in different light environments.In our study,P.trinervis was grown for 8 months under light filtered by three different colored films.The three treatments were blue film,green film,and white plastic film.The effects of blue(B),green(G),and white(W)light on photosynthetic pigment content,absolute growth,photosynthetic parameters,soluble sugar content,and chlorophyll fluorescence parameters were studied,respectively.Compared to the Wtreatment,the chlorophyll a and b,carotenoids,total chlorophyll content(a+b),absolute growth of seedling height,net photosynthetic rate(PN),water use efficiency(WUE),total soluble sugars,sucrose,and nonphotochemical quenching(NPQ)of P.trinervis were significantly increased under B treatment.Meanwhile,chlorophyll a and b,carotenoids,total chlorophyll(a+b),transpiration rate(Tr),intercellular CO_(2) concentration(Ci),stomatal conductance(gs),absolute growth of seedling height and leaf length,reducing sugar,total soluble sugar content,and NPQ were significantly increased under G treatment.The results showed that the absolute growth and chlorophyll content of P.trinervis were increased under B light,while the sugar and photosynthetic parameters were increased under G light.Additional studies may look into how B light impacts absolute growth and promotional mechanisms,as well as how G light affects the accumulation of sugar levels.

Incorporating topographic factors in nonlinear mixed-effects models for aboveground biomass of natural Simao pine in Yunnan,China

A total of 128 Simao pine trees （Pinus kesiya var. langbianensis） from three regions of Pu＇er City, Yunnan Province, People＇s Republic of China, were destructively sampled to obtain tree aboveground biomass （AGB）. Tree variables such as diameter at breast height and total height, and topographical factors such as altitude, aspect of slope, and degree of slope were recorded. We considered the region and site quality classes as the ran- dom-effects, and the topographic variables as the fixed- effects. We fitted a total of eight models as follows： least- squares nonlinear models （BM）, least-squares nonlinear models with the topographic factors （BMT）, nonlinear mixed-effects models with region as single random-effects （NLME-RE）, nonlinear mixed-effects models with site as single random-effects （NLME-SE）, nonlinear mixed-ef- fects models with the two-level nested region and site random-effects （TLNLME）, NLME-RE with the fixed-ef- fects of topographic factors （NLMET-RE）, NLME-SE with the fixed-effects of topographic factors （NLMET-SE）, and TLNLME with the fixed-effects of topographic factors （TLNLMET）. The eight models were compared by modelfitting and prediction statistics. The results showed： model fitting was improved by considering random-effects of region or site, or both. The models with the fixed-effects of topographic factors had better model fitting. According to AIC and BIC, the model fitting was ranked as TLNLME 〉 NLMET-RE 〉 NLME-RE.〉 NLMET-SE 〉 TLNLMET 〉 NLME-SE 〉 BMT 〉 BM. The differences among these models for model prediction were small. The model pre- diction was ranked as TLNLME 〉 NLME-RE 〉 NLME- SE 〉 NLMET-RE 〉 NLMET-SE 〉 TLNLMET 〉 BMT 〉 BM. However, all eight models had relatively high prediction precision （〉90 %）. Thus, the best model should be chosen based on the available data when using the model to predict individual tree AGB.

DNA barcoding and molecular phylogeny of Dumasia(Fabaceae:Phaseoleae)reveals a cryptic lineage

Dumasia taxonomy and classification have long been problematic.Species within this genus have few morphological differences and plants without flowers or fruits are difficult to accurately identify.In this study,we evaluated the ability of six DNA barcoding sequences,one nuclear(ITS)and five chloroplast regions(trnH-psbA,matK,rbcL,trnL-trnF,psbB-psbF),to efficiently identify Dumasia species.Most single markers or their combinations identify obvious barcoding gaps between intraspecific and interspecific genetic variation.Most combined analyses including ITS showed good species resolution and identification efficiency.We therefore suggest that ITS alone or a combination of ITS with any cpDNA marker are most suitable for DNA barcoding of Dumasia.The phylogenetic analyses clearly indicated that Dumasia yunnanensis is not monophyletic and is separated as two independent branches,which may result from cryptic differentiation.Our results demonstrate that molecular data can deepen the comprehension of taxonomy of Dumasia and provide an efficient approach for identification of the species.

Cloning and expression analysis of HXK1 gene from Jatropha curcas L.

HXK(Hexokinase)gene family and the role of JcHXK1 in Jatropha curcas L.were explored.Totally 4 HXK genes JcHXK1,JcHXK2,JcHXK3 and JcHKL1 were identified and complete ORF of JcHXK1 was cloned.Functional domain,phylogenetic evolution and low-temperature expression characteristics were analyzed.Results showed that full-length JcHXK1 cDNA was 1497 bp,encoding 498 amino acids with molecular weight of 53.81 kDa and pI of 5.03.Further phylogenetic evolutionary analysis demonstrated HXK1 protein was clustered into 6 small branches and 2 large branches.Sequence alignment showed that HXK1 contained several conserved glycine residues and hydrophobic channels.Prokaryotic expression vector of JcHXK1 was constructed and 12%SDS-PAGE detection showed that it was highly expressed in E.coli.These research was expected to lay a foundation for further gene functional verification and cold signal transduction mechanism for HXK1 in Jatropha curcas L.

Nuclear phylotranscriptomics and phylogenomics support numerous polyploidization events and hypotheses for the evolution of rhizobial nitrogenfixing symbiosis in Fabaceae

Fabaceae are the third largest angiosperm family,with 765 genera and~19500 species.They are important both economically and ecologically,and global Fabaceae crops are intensively studied in part for their nitrogen-fixing ability.However,resolution of the intrasubfamilial Fabaceae phylogeny and divergence times has remained elusive,precluding a reconstruction of the evolutionary history of symbiotic nitrogen fixation in Fabaceae.Here,we report a highly resolved phylogeny using>1500 nuclear genes from newly sequenced transcriptomes and genomes of 391 species,along with other datasets,for a total of 463 legumes spanning all 6 subfamilies and 333 of 765 genera.The subfamilies are maximally supported as mono-phyletic.The clade comprising subfamilies Cercidoideae and Detarioideae is sister to the remaining legumes,and Duparquetioideae and Dialioideae are successive sisters to the clade of Papilionoideae and Caesalpinioideae.Molecular clock estimation revealed an early radiation of subfamilies near the K/Pg boundary,marked by mass extinction,and subsequent divergence of most tribe-level clades within~15 million years.Phylogenomic analyses of thousands of gene families support 28 proposed putative whole-genome duplication/whole-genome triplication events across Fabaceae,including those at the ancestors of Fabaceae and five of the subfamilies,and further analyses supported the Fabaceae ancestral polyploidy.The evolution of rhizobial nitrogen-fixing nodulation in Fabaceae was probed by ancestral character reconstruction and phylogenetic analyses of related gene families and the results support the hypotheses of one or two switches)to rhizobial nodulation followed by multiple losses.Collectively,these results provide a foundation for further morphological and functional evolutionary analyses across Fabaceae.

Hybrid speciation via inheritance of alternate alleles of parental isolating genes

It is increasingly realized that homoploid hybrid speciation(HHS),which involves no change in chromosome number,is an important mechanism of speciation.HHS will likely increase in frequency as ecological and geographical barriers between species are continuing to be disrupted by human activities.HHS requires the establishment of reproductive isolation between a hybrid and its parents,but the underlying genes and genetic mechanisms remain largely unknown.In this study,we reveal by integrated approaches that reproductive isolation originates in one homoploid hybrid plant species through the inheritance of altemate alleles at genes that determine parental premating isolation.The parent species of this hybrid species are reproductively isolated by differences in flowering time and survivorship on soils containing high concentrations of iron.We found that the hybrid species inherits alleles of parental isolating major genes related to flowering time from one parent and alleles of major genes related to iron tolerance from the other parent.In this way,it became reproductively isolated from one parent by the difference in flowering time and from the other by habitat adaptation(iron tolerance).These findings and further modeling results suggest that HHS may occur relatively easily via the inheritance of alternate parental premating isolating genes and barriers.

A Phytochrome B-PIF4-MYC2/MYC4 module inhibits secondary cell wall thickening in response to shaded light

Secondary cell walls(SCWs)in stem cells provide mechanical strength and structural support for growth.SCW thickening varies under different light conditions.Our previous study revealed that blue light enhances SCW thickening through the redundant function of MYC2 and MYC4 directed by CRYPTOCHROME1(CRY1)signaling in fiber cells of the Arabidopsis inflorescence stem.In this study,we find that the Arabidopsis PHYTOCHROME B mutant phyB displays thinner SCWs in stem fibers,but thicker SCWs are deposited in the PHYTOCHROME INTERACTING FACTOR(PIF)quadruple mutant pif1pif3pif4pif5(pifq).The shaded light condition with a low ratio of red to far-red light inhibits stem SCW thickening.PIF4 interacts with MYC2 and MYC4 to affect their localization in nuclei,and this interaction results in inhibition of the MYCs’transactivation activity on the NST1 promoter.Genetic evidence shows that regulation of SCW thickening by PIFs is dependent on MYC2/MYC4 function.Together,the results of this study reveal a PHYB-PIF4-MYC2/MYC4 module that inhibits SCW thickening in fiber cells of the Arabidopsis stem.